Phase coexistence, magnetic inhomogeneity, and disorder in the charge-ordered state ofPr2/3Ca1/3MnO3

The coexistence of ferromagnetic metallic and antiferromagnetic charge-ordered (CO) states in ${\mathrm{Pr}}_{2/3}{\mathrm{Ca}}_{1/3}{\mathrm{MnO}}_3$ has been investigated using zero-field muon spin relaxation, neutron diffraction, calorimetric, and magnetic measurements. Calorimetric data evidence a high degree of disorder below the CO transition. The data are consistent with large antiferromagnetic (AFM) CO regions containing structural and magnetic inhomogeneities densely scattered. Below the charge order temperature ${(T}_{\mathrm{CO}}\approx 220\mathrm{K})$ the dominant relaxation mechanism of the muon polarization is based on ferromagnetic Mn-Mn correlations and the spin-lattice relaxation rate is peaked at $T_C$ instead of $T_N.$ The results agree with a spatial distribution of ferromagnetic and AFM regions strongly interpenetrated. The presence of local magnetic order in the whole sample is only achieved just below $T_C\approx 120\mathrm{K}.$